1. Field of the Invention
The present invention relates to a honeycomb structure.
2. Discussion of the Background
In recent years, particulate matter (hereinafter, also referred to as “PM”) such as soot contained in exhaust gases discharged from internal combustion engines of vehicles such as buses and trucks, and construction machines has raised serious problems as contaminants harmful to the environment and the human body. For this reason, a honeycomb structure including a porous ceramic, in which a plurality of honeycomb fired bodies, each having a large number of cells longitudinally disposed in parallel with one another with a cell wall therebetween and including as a main component a porous ceramic made of a silicon carbide, are bonded to one another by interposing an adhesive layer to form a ceramic block and a sealing material layer is formed on a peripheral portion, is proposed as a filter which captures the PM in exhaust gases and purifies the exhaust gases.
Further, a honeycomb structure capable of converting a toxic component in exhaust gases by supporting a catalyst on a cell wall has been also proposed.
In a case where a honeycomb structure of this kind is used as an exhaust gas purifying filter, a regenerating treatment of the honeycomb structure by burning to remove captured PM is carried out after a certain time period of use. The regenerated honeycomb structure is repeatedly used as the exhaust gas purifying filter. Here, the honeycomb structure is to be exposed to a high temperature by a burning of PM during the regenerating treatment.
When honeycomb fired bodies are adhered to one another to manufacture a ceramic block upon manufacturing the honeycomb structure of this kind, a spacer (cavity-holding member) as disclosed in JP2002-102627A, WO03/031371A, and JP2004-283669A is used to maintain an even thickness of the adhesive layer.
The contents of JP2002-102627A, WO03/031371A and JP2004-283669A are incorporated herein by reference in their entirety.